Sencore 12AU7 tube

I got hold of a bunch of Sencore Japan 12AU7's, looks like manufacturing date is '64.
Anybody has had any experience with Sencores?, thanks.
On a somewhat separate note, tube testers. There seem to be a lot of different models out there, what are the more reliable makes/models out there, thanks.

Be interesting to find out who actually made them ... I do know Sencore used 12AU7's in some of their tube testers to provide a reference signal ...

Matshushita? Rumor has it they used the same tooling as Mullard ...

Lot of options for tube testers for classic gear. I like my Precision 920. Has the expansion kit for octals and several other late variety tube designs and the latest - mid '70's anyway - data roll.

One thing I haven't figured out yet ... how to test the tubes in the tube tester to make sure the tube tester is testing tubes right ...

Well it says Sencore Japan, 64-04, 12AU7 and thats about it. They seem to be grey plate units.
Ah, to test the tube tester......indeed!